Why my Dell battery have a strip of LED lights

Original Dell J60J5 laptop battery 7.6V 7237mAh 

Battery rating: 7.6V
Battery capacity: 7237mAh (55Wh)
Battery cells 6-cell
Type: rechargeable Li-Polymer original battery
Battery color: Black
Warranty: 9 Months  

Most Dell batteries have an LED indicator that allows users to see how much run time and how much overall battery life are available at the touch of a button. 

To check battery charge, press the button and the number of lights that appear will tell you charge status. If all lights appear, you have a fully charged battery. Each light that appears accounts for approximately 20% charge.

To check the battery health, press and hold the status button on the battery charge gauge for at least 3 seconds. If no lights appear, the battery is in good condition and approximately more than 80 percent of its original charge capacity remains. Each light represents incremental degradation. If five lights appear, approximately less than 60 percent of the charge capacity remains, and you should consider replacing the battery.